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| author | Xin Long <lucien.xin@gmail.com> | 2018-08-27 13:38:31 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-15 10:42:56 +0300 |
| commit | 36bf8bc54a59c14ce9b27283ff9f2225908fce1f (patch) | |
| tree | 7486727de0a1de638a471980144653c5e35e226d /net/sctp | |
| parent | d669bd62756ff89c3d49fc9e23973087ea27dfdd (diff) | |
| download | linux-36bf8bc54a59c14ce9b27283ff9f2225908fce1f.tar.xz | |
sctp: hold transport before accessing its asoc in sctp_transport_get_next
[ Upstream commit bab1be79a5169ac748d8292b20c86d874022d7ba ]
As Marcelo noticed, in sctp_transport_get_next, it is iterating over
transports but then also accessing the association directly, without
checking any refcnts before that, which can cause an use-after-free
Read.
So fix it by holding transport before accessing the association. With
that, sctp_transport_hold calls can be removed in the later places.
Fixes: 626d16f50f39 ("sctp: export some apis or variables for sctp_diag and reuse some for proc")
Reported-by: syzbot+fe62a0c9aa6a85c6de16@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/sctp')
| -rw-r--r-- | net/sctp/proc.c | 4 | ||||
| -rw-r--r-- | net/sctp/socket.c | 22 |
2 files changed, 15 insertions, 11 deletions
diff --git a/net/sctp/proc.c b/net/sctp/proc.c index 206377fe91ec..fd7f23566ed6 100644 --- a/net/sctp/proc.c +++ b/net/sctp/proc.c @@ -337,8 +337,6 @@ static int sctp_assocs_seq_show(struct seq_file *seq, void *v) } transport = (struct sctp_transport *)v; - if (!sctp_transport_hold(transport)) - return 0; assoc = transport->asoc; epb = &assoc->base; sk = epb->sk; @@ -428,8 +426,6 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, void *v) } transport = (struct sctp_transport *)v; - if (!sctp_transport_hold(transport)) - return 0; assoc = transport->asoc; list_for_each_entry_rcu(tsp, &assoc->peer.transport_addr_list, diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 78f38056fca6..64d2d9ea2f8c 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4476,9 +4476,14 @@ struct sctp_transport *sctp_transport_get_next(struct net *net, break; } + if (!sctp_transport_hold(t)) + continue; + if (net_eq(sock_net(t->asoc->base.sk), net) && t->asoc->peer.primary_path == t) break; + + sctp_transport_put(t); } return t; @@ -4488,13 +4493,18 @@ struct sctp_transport *sctp_transport_get_idx(struct net *net, struct rhashtable_iter *iter, int pos) { - void *obj = SEQ_START_TOKEN; + struct sctp_transport *t; - while (pos && (obj = sctp_transport_get_next(net, iter)) && - !IS_ERR(obj)) - pos--; + if (!pos) + return SEQ_START_TOKEN; - return obj; + while ((t = sctp_transport_get_next(net, iter)) && !IS_ERR(t)) { + if (!--pos) + break; + sctp_transport_put(t); + } + + return t; } int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), @@ -4556,8 +4566,6 @@ int sctp_for_each_transport(int (*cb)(struct sctp_transport *, void *), for (; !IS_ERR_OR_NULL(obj); obj = sctp_transport_get_next(net, &hti)) { struct sctp_transport *transport = obj; - if (!sctp_transport_hold(transport)) - continue; err = cb(transport, p); sctp_transport_put(transport); if (err) |